COVID-19 testing firm refutes FDA claim, insists antigen tests have higher sensitivity rate

COVID-19 testing firm LabX Corp. refuted the claims of the Philippines’ Food and Drug Administration (FDA) that antigen tests have low sensitivity rate.

In a television interview, LabX Corp. CEO Thomas Navasero said antigen test has 93.8% sensitivity rate, and not only 30 to 80% as claimed by the FDA.

“Antigen tests have sensitivity rate of around 93% contrary to the claim of Philippine FDA Director General Eric Domingo that antigen tests have only 34 to 80% sensitivity rate,” he said on Friday.

Navasero explained that sensitivity in antigen tests measures the false negative test results for the virus.

“In the last four to six months, technology and research have improved the sensitivity of antigen testing. The 93.8% is probably the highest sensitivity in the world,” he added.

Navasero noted that antigen tests have 100% specificity rate that it can fully identify if a patient is positive for the virus.

According to him, the US and many European countries are using antigen tests as the primary COVID-19 testing method, along with the reverse transcription-polymerase chain reaction (RT-PCR) tests.

He explained that both RT-PCR and antigen tests can identify the protein of the coronavirus, resulting in higher chances of detecting the virus’ presence in a patient.

Navasero said he hopes that antigen tests can also be recognized as the gold standard for COVID-19 testing, as it can detect the virus in 15 minutes.

For him, antigen tests are more accessible, more accurate and more affordable.

“At the cost of one BSL-2 (Biosafety Level 2) laboratory for COVID-19 which is about P25 million, that can acquire 100 machines for antigen testing," Navasero said.

"In the fight against COVID-19, this is a game changer and even the government can afford to conduct mass testing in the Philippines. We can actually do one million tests per day with one thousand machines,” he added.

In a media briefing on Wednesday, Domingo underscored that PCR-based testing is still the gold standard to diagnose COVID-19. Citing the World Health Organization, Domingo said the sensitivity of antigen tests varies only from 34% to 80%.

Domingo made the statement when asked about the status of the validation for the Sofia 2 SARS-CoV2 antigen test product.

Like PCR-based testing, antigen tests use swabs to collect a sample of mucus from a patient’s nose or throat, he explained. And like antibody tests, antigen tests also yield fast results with a turnaround time of only about 15 minutes, he added.

“Itong antigen test. Isang bagong class na naman ‘to ng mga test natin. Dati, meron tayong PCR test—ito pa rin ang gold standard. Pangalawa, ‘yung mga antibody test na nagche-check ng anti-body,” he said.

“'Yung antigen naman, nagsa-swab din po talaga. Tapos naghahanap siya ng parte ng virus na ma-identify doon sa test kit. It takes about 15 minutes. Pero hindi pa rin siya kasing accurate ng PCR,” he said.

On Sunday, Domingo told GMA News Online that the FDA already approved some antigen testing kit products.

Earlier, the Philippine Society of Microbiology and Infectious Diseases said that using rapid antibody tests for COVID-19 may lead to “unintended harm” given the high possibility of a false positive.

As of Friday, the FDA has approved 78 antibody test kit products, 53 immunoassay, and 72 PCR-bases test kit products. —KG, GMA News